Shah et al. Macromolecules 2000, 33, 597-605 (2000), describes the use of atom transfer radical polymerization (ATRP) to grow polymer brushes on monolayers of (BrC(CH3)2COO(CH2)10S)2 that have been self-assembled onto gold substrates. The polymer brushes act as barriers to wet chemical etchants of gold enabling patterns to be transferred into the gold substrates underlying the brushes.
Chapman et al., Langmuir, 1225-1233, Vol. 17, No. 4 (2001), describes the use of grafting to produce a protein and bacteria resistant surface. In this process, polyamines are reacted with carboxylic anhydride groups contained in the self-assembled monolayers (SAMs) in order to produce a polymer layer having multiple amino groups, which are then acylated to introduce protein and bacteria resistant functional groups.
Kong et al, Macromolecules, 34, 1837-1844 (2000), describes a process for preparing etching barriers for microlithographic applications.
This process involves using atom transfer radical polymerization (ATRP) in conjunction with two different SAMs to grow poly(methyl methacrylate)(PMMA) and poly(acrylamide) (PAAM) homopolymer brushes on an initiator coated silicon surface.
Although other polymers have been assembled into monolayers onto substrates so as to produce surfaces resistant to the adsorption of proteins and biological cells, this invention discloses new surface materials, i.e. PEGAA monomers that may be grown through an SATRP process in a stepwise and controlled manner on SAMs comprising initiator molecules and optionally spacer molecules. By using this process, a polymeric PEGAA film gradient having the desired graded increase/decrease in thickness can be easily grown on the moiety accepting surface of a substrate having any shape. The process according to this invention also enables a polymeric PEGAA film gradient having a particular increase/decrease in thickness, or polymer chain density to be efficiently and accurately deposited on any moiety accepting substrate surface, wherein the increase/decrease in thickness that is specified is within the range of from about 0.5 nm to about 5000 nm and the polymer chain density specified is within the range of from about 0.1 to about 100%.
The present invention advantageously enables the graded increase of the PEGAA film gradient to be determined by adjusting either the polymer chain length, or the molecular weight and concentration of the monomer from which the repeat units of the PEGAA polymer are derived. This process further allows the graded increase of the PEGAA film gradient to be controlled by the length of time the polymer chains are permitted to grow/polymerize.